AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Whole Lithospheric Folding as a Mechanism of Basin Formation and Tectonic Implications for Gondwana Evolution: Evidence from the Palmyride Trough, Syria
(1) BG Wood Consultant, Chilson, United Kingdom.
Data from the Palmyride Trough of Syria do not support a rift origin of this intra-plate basin. The trough has filled with six successor basins since the late Palaeozoic, each basin sequence consisting of low energy, shallow water sediments recording cyclical drowning and drying. Late cycle and inter-cycle regional erosion and volcanism suggest a tectonic influence on cycle termination and basin renewal. New isocore maps show a narrowing of nested troughs through time, increasing structural segmentation and regional counter clockwise rotation.
Lithospheric folding is proposed for trough initiation in the late Palaeozoic with subsequent cyclical deposition, exposure and deformation occurring as a reaction to a naturally occurring decrease in the underlying fold wavelength and regional rotation. Shortening across the basin, since the late Palaeozoic, has been minor, probably less than 20-30 kilometres. Basin longevity and stratigraphic history and limited shortening precludes the view that formation and deformation of the Palmyride trough occurred solely during Tertiary left-lateral movement on the Levant Fracture. An alternate mechanism is needed.
Although not often considered contiguous, Egypt & Syria share a common late Palaeozoic and Mesozoic structural and sedimentary history. It is proposed that this greater Eastern Mediterranean Basin formed as a lithospheric, compressional downwarp during the disintegration of Gondwana and a single, constant, unidirectional, far-field force from the southeast best explains the compression and subsequent narrowing and counter clockwise rotation of successor basins. There is no need to introduce constantly changing stress fields through time to account for local and regional patterns. Independent support for this new tectonic model comes from the rotational history of Afro-Arabia derived from the study of magnetic stripping of the surrounding Mesozoic oceans which matches that derived from the rotation of Palmyride Trough successor basins.
Gondwana partitioning by northwest oriented rifting, sedimentation in plate-scale northeast oriented compressional downwarps and a history of continental scale counter clockwise rotation, all driven by a constant, far-field, northwest oriented force, fits regional geologic and structural patterns across the present day African and Arabian plates. Understanding regional deformation through time allows for prediction of sedimentation patterns from tectonic to local scale.